Apparatus is presently available for handling counting and stacking sheets such as paper currency, checks, food stamps and the like. Such apparatus which is described for example in U.S. Pat. No. 4,474,365 issued Oct. 2 , 1984 and assigned to the assignee of the present application, discloses cooperating feed and stripper means for advancing sheets from an input tray one at a time for examination by sensing devices and for accelerating the examined sheets which are then delivered to an output tray. It is extremely desirable in the handling of such documents to be assured that the documents are in fact moved one at a time through the sensing region since the feeding of overlapping or multiple fed documents, as well as shorter than normal documents, has a negative effect upon the counting accuracy of the apparatus.